柱塞零件圆柱度公差的技术测量

基于活门轴(又称为柱塞)圆柱度公差是圆柱面横截面形状误差和轴截面形位误差的综合的原理,研制柱塞圆柱度公差专用测量仪。通过测量柱塞零件表面的径向全跳动公差实现柱塞工作面圆柱度公差的合格性评定。     

1 种高精度大型阶梯轴圆柱轮廓测量模型

为了提高大型阶梯轴回转部件圆柱轮廓的测量精度,提出1种考虑偏心量、工件倾斜及传感器测头偏移的3偏置测量模型。分析了综合偏置误差对阶梯轴截面圆柱轮廓残余误差的影响及偏置误差在不同工件半径下对圆柱轮廓测量结果的影响,实现了阶梯轴圆柱轮廓精度的准确评定。为了验证3偏置圆柱轮廓测量模型的有效性,采用超精密航空发动机测量仪对大直径阶梯轴的圆柱轮廓进行了测量与评定。结果表明:与传统双偏置测量模型相比,3偏置圆柱轮廓测量模型所评定的大半径阶梯轴同轴度的准确性提高了9.39μm;阶梯轴半径越大,测量精度越高。     

圆柱滚子误差评定及其加工均匀性评价

通过对圆柱滚子研磨轨迹均匀性的研究,建立研磨轨迹加工均匀性的评价方法,为获得较优的研磨轨迹分布提供依据。同时为减少圆柱滚子的测量误差,采用最小区域法对圆柱度误差进行评定。     

高精度圆柱度测量方法

针对某军机喷嘴主衬套和外贸关键件的圆柱度精度要求较高、测量误差相对较大的问题，利用公司新进口的新型圆柱度测量仪及其软件，采用半径测量法，运用误差分析理论，分析了测量过程的主要误差来源和影响因素；结合加工实际情况选择了相应的评定方法，实现了高精度圆柱度的准确测量；制定了操作流程，保证了准确的测量结果，为产品生产过程的质量控制提供了准确依据。     

高精度圆柱度测量方法

针对某军机喷嘴主衬套和外贸关键件的圆柱度精度要求较高、测量误差相对较大的问题,利用公司新进口的新型圆柱度测量仪及其软件,采用半径测量法,运用误差分析理论,分析了测量过程的主要误差来源和影响因素;结合加工实际情况选择了相应的评定方法,实现了高精度圆柱度的准确测量;制定了操作流程,保证了准确的测量结果,为产品生产过程的质量控制提供了准确依据.     

谈谈如何解决圆柱度的检测问题

目前对圆柱度的使用存有两种意见。一种意见认为:鉴于当前对圆柱的检测尚缺少相应的设备,主张图样上尽量少用或者不用圆柱度,而用与圆柱度有关的特征参数公差代替之。另一种意见认为:圆柱度公差用其它公差代替存在许多弊病,直接影响设计质量。所以主张对确实有圆柱度要求的地方就应该标注圆柱度,不宜用其它项目代替。检测时可以通过与其有关的特征参数误差间接评定圆柱度。笔者认为,后者意见更可取。关键是哪些特征参数与圆柱度有关?其数值又如何处理?这些目前尚无明确规定。本文就这一问题谈点个人看法,希望能对圆柱度的检测有所帮助。     

一种实用的圆柱度近似测量方法

圆柱形结构要素在零件结构中占的比例很高,精度要求高的圆柱形要素零件很重要的一个技术指标为圆柱度.本文介绍了用分解法来测量圆柱度的近似测量方法,此种方法简便、有效、可靠,特别适用于生产现场圆柱度误差的测量,也适用于尚未购置圆柱度的企业.     

圆度、圆柱度、轴线直线度误差电算法

在GB1958—80附录一“检测方案”中,对圆度误差,圆柱度误差、轴线直线度误差的检测,均提到了用电子计算机按最小条件计算其误差的问题。现将我们利用电子计算机计算上述三项误差的方法介绍如下。     

圆度误差评定方法及圆度误差统计分布的研究

现行的形状误差标准和形状误差评定方法是建立在几何学基础上的形状公差带问题.作者在研究回转体零件圆度误差评定方法的基础上,提出统计圆度误差的概率分布,并进行实验测量和数据采集,将拟合后的圆度误差利用数理统计的方法得出统计分布结果,证明符合一定的概率分布规律.     

基于内圈滚道廓形的圆柱滚子轴承旋转精度

在轴承几何关系和运动关系分析基础上,建立了考虑内圈滚道廓形的圆柱滚子轴承径向跳动数学模型,分析了内圈滚道圆度误差幅值、谐波阶次、滚子个数以及径向游隙对轴承旋转精度的影响规律,并验证了模型的正确性.结果表明:内圈滚道的圆度误差对轴承旋转精度的影响较大,内圈滚道圆度误差幅值对轴承旋转精度影响较大,内圈滚道低阶谐波对轴承旋转精度的影响较高阶谐波显著;当内圈滚道谐波阶次为滚子个数的整数倍时,轴承旋转精度显著下降;减小内圈滚道圆度误差幅值能有效提高圆柱滚子轴承的旋转精度.      

旋转矩形截面弯管内流动特性的研究

本文利用数值计算方法研究了三种旋转矩形截面（η＝1，η＞1，η＜1）弯管内的粘性流动，分析了在离心力和科氏力共同作用下二次流动、轴向主流、摩擦系数比各参数的变化情况，所得的结果与已有文献的结果（数值结果和实验结果）非吻合，计算结果表明：对于宽高比η≤1的矩形截面，截面上最多可以存在8个涡；若η＞1，同上最多可以出现6个涡；摩擦系数比和二次流函数量大值在F≈－1时取得最小值，；计算结果还表明，η对高速旋转弯管内的摩擦系数比的影响程度要明显高于对静止的弯管内的摩擦系数比的影响程序，最后本文给出η＝1时的旋转矩形弯管内摩擦系数的计算公式。     

有1的结合环的交换性

本文证明了有１的结合环的两个交换性定理，推广了Ｇｉｒｉ．Ｒ．Ｄ等人在参考文献１中的结果。     

差分方程yn+1=A+yn/(kΣi=1αiyn-i)的全局吸引性

研究差分方程yn+1=A+yn/(kΣi=1αiyn-i),N=0,1,...正解的稳定性,其中,A∈(0,∞),αi∈(0,∞),kΣi=1αi=k,k≥1且是整数,初始条件y-k,...,y0为任意正数.阐述并证明该方程的惟一正平衡点是全局吸引子且吸引域取决于方程的系数.     

SAR resolution in the presence of phase errors

The author analyzes the effects of phase errors on synthetic aperture radar (SAR). The theory is applied to the following question: how does the achievable resolution vary with the carrier frequency when optimum quadratic focus and/or optimum processing interval (synthetic aperture length) are used? Numerous related results are given, so that much of the material is tutorial. For phase errors corresponding to uncompensated motion, the best achievable RMS resolution with any phase error spectrum satisfies the derived equation. For motion-induced phase errors it is seen that resolution improves with increasing carrier frequency when the first term in the expression applies (e.g. for phase errors concentrated at low frequencies) and resolution is independent of carrier frequency when R δ/v/v is the smaller term (e.g. with broad band or high frequency phase errors)     

军事计量的挑战与对策

分析了军事计量的特点与面临的困难和挑战：1）人才队伍;2）知识体系;3）技术体系;4）计量标准设施。讨论了军事计量所必需解决的技术问题与所面临的未来技术挑战。提出了军事计量应对挑战的对策：1）顶层设计;2）法规制定;3）基础研究;4）构建独立知识体系;5）强化核心能力建设;6）军民融合。     

An Algebraic Solution of the GPS Equations

The global positioning system (GPS) equations are usually solved with an application of Newton's method or a variant thereof: Xn+1 = xn + H-1(t - f(xn)). (1) Here x is a vector comprising the user position coordinates together with clock offset, t is a vector of tour pseudorange measurements, and H is a measurement matrix of partial derivatives H = fx· In fact the first fix of a Kalman filter provides a solution of this type. If more than four pseudoranges are available for extended batch processing, H-1 may be replaced by a generalized inverse (HTWH)-1HTW, where W is a positive definite weighting matrix (usually taken to be the inverse of the measurement covariance matrix). This paper introduces a new method of solution that is algebraic and noniterative in nature, computationally efficient and numerically stable, admits extended batch processing, improves accuracy in bad geometric dilution of precision (GDOP) situations, and allows a "cold start" in deep space applications.     

大迎角飞行品质的研究进展

分析了飞行包线向低速大迎角扩展后飞行品质研究面临的几个重要方面,即需要提供直到充分过失速迎角的飞行品质指标,这是设计飞控系统的依据之一：纵,横,航向操纵效能要求,这是配置,裁减操纵面的依据,机动任务集,这对于提出品质指标与操纵效能要求,及早发现飞机缺陷和全面评价飞机系统的战术效能等工作都有重要意义,总结有关的研究思路以及目前的进展,并给出了一些初步结论。     

Voyager Observations of the Magnetic Field in the Distant Heliosphere

The latitudinal structure of the heliospheric magnetic field during much of the solar cycle is determined by a "sector zone", in which both positive and negative magnetic polarities are observed, and by the unipolar regions above and below the sector zone. Distinct corotating streams and interactions regions are found primarily in the sector zone during the declining phase of the solar cycle. Within a few AU, the streams and interaction regions are distinct and are related to solar features. A restructuring of the solar wind occurs between 1 AU and 15 AU, in which the isolated streams, interaction regions and shocks merge to form compound streams and merged interaction regions ("MIRs"). Memory of the source conditions is lost in this process. In the region between 30 AU and the termination shock (the "distant heliosphere"), the pressure of interstellar pickup protons dominates that of the magnetic field and solar wind particles and largely controls the dynamical processes. During 1983 and 1994, corotating streams and corotating interaction regions were observed at 1 AU. Merged interaction regions were observed at 15 AU in 1983, but not at 45 AU during 1994. This result suggests a further restructuring of the solar wind in the distant heliosphere, but variations from one solar cycle to the next might also contribute to the result. Approaching solar minimum in 1996, the latitudinal extent of the sector zone decreased, and Voyager 2 gradually entered the unipolar region below it. The speed was lower in the sector zone than below it. At Voyagers 1 and 2, the change in cosmic ray intensity is related to the magnetic field strength during each year from 1983 through 1996. The magnetic field strength has a multifractal distribution throughout the heliosphere. This fundamental symmetry of the heliosphere has not been incorporated explicitly in cosmic ray propagation models.     

非线性负阻尼极限环型角位移振荡运动定量分析

从某飞行器两次飞行记录的俯仰角θ、偏航角Ψ观测值出发,分别采用对Van der Pol方程描述的θ和Ψ的角位移振荡运动微分方程进行气动参数辨识,和对观测值θ-狋、Ψ-t曲线的外包络线进行参数拟合两种分析方法,对该飞行器的角位移振荡运动特性进行了定量分析。两种分析方法取得了较为一致的结果,并证明该飞行器飞行中出现的锥形振荡运动是典型的非线性负阻尼极限环型的振荡运动,获得了非线性负阻尼极限环型气动阻尼力矩的典型表达式。分析结果表明非线性负阻尼极限环类型的气动阻尼能够导致飞行器出现动不稳定。     

Digital system design in the presence of single event upsets

The authors consider the effects of single event upsets (SEUs) on digital systems, and show techniques for designing reliable systems with current levels of SEU protection. Three main systems are discussed: main memory, logic, and cache memory. A design for the main and cache memory subsystems that are SEU protected is also described. With SEU defined in bit days p, and using single error correction, it is shown that for all subsystems considered, an effective upset rate which is proportional to the product of p² and the time between corrections, or scrub time, can be obtained. Data for memory chip size and performance derived from the gallium-arsenide (GaAs) pilot lines funded by the Defense Advanced Research Projects Agency (DARPA) throughout the 1980s are used